Neurobiology and Behavior

the BRAIN

Nervous System Peripheral nervous system (PNS) sensory and motor neurons that connect the CNS to the rest of the body [cranial, spinal, and ganglia nerves] Central nervous system (CNS)- brain and spinal cord Autonomic- controls self regulation of internal organs and glands Somatic- controls voluntary movements of skeletal muscles [response to external stimuli, ex. Reflexes] Sympathetic (arousing): dilated pupils; accelerated heart beat; stomach/ pancreas inhibit digestion; liver stimulates glucose release; adrenal gland/ kidneys secretes epine./ norepine; bladder relaxed; males release testosterone Parasympathetic (calming): pupils contracted; slowed heartbeat; stomach’s digestion stimulated; gallbladder stimulated; contracted bladder; blood flow to sex organs. Enteric- controls digestive tract, pancreas, and gallbladder; controls secretion

Brainstem- innermost, evolutionary, oldest part of the brain. “lower brain” –Medulla Oblongata- heartbeat and breathing –Pons- nuclei in medulla that regulate breathing centers –Midbrain- centers for receipt and integration of sensory information »Inferior (auditory) and superior (visual) colliculi Cerebellum- “little brain,” regulates balance and voluntary movement. Coordination and “error checking” – position of joints and lengths of muscles and information from auditory and visual systems. Learns and remembers motor responses, (hand-eye coordination) Diencephalon –Epithalamus- area that produces cerebrospinal fluid from blood –Thalamus- messages to sensory areas and replies to cerebellum & medulla, to regulate emotion and arousal –Hypothalamus- HOMEOSTASIS!!! eat, drink, body temp., etc.; endocrine system; emotion. pleasure center (Olds & Milner), sexual and mating behavior, fight-or-flight. Limbic system- emotions (fear & aggression), drives( food& sex) Hippocampus- memory Amygdala- emotion

Cerebrum Right and Left Cerebral Hemispheres Cerebral Cortex- outermost layer, surface of the brain. Covered in Gray matter: neurons without myelin sheath Sensory information is analyzed, motor commands are issued, language is generated. Neocortex: outermost layer of cerebrum in mammals. Folded structure so that brain has larger surface area- more area for neurons and thinking communication. White matter: neurons with myelin sheath –Inner tissue of the brain with basal nuclei- plan and learn movement sequence Split/ Divided Brain: Corpus Callosum: band of axons connects the 2 hemispheres; relays messages, enables communication 4 Lobes: Frontal (speaking, muscle movements, making plans and judgments); Parietal (sensory cortex); Occipital (visual areas); Temporal (auditory areas) Primary Motor Cortex: rear of frontal lobe; Primary Somatosensory Cortex: fornt of parietal lobe –Neurons distributed according to part of body that generates sensory output; cortical surface area related to number of a) sensory neurons that innervate that part or b) motor neurons that control those muscles Ventricles within the brain, past gray and white matter, contain cerebrospinal fluid –Fluid cushions the brain and also supplies nutrients and hormones to areas of brain; removes waste

Lateralization –Left: language, math, logic, serial operations, speedy muscle control, visual and auditory details –Right: patterns, face, spatial, nonverbal thinking, emotional processing, multi-information generation. Connections between images and whole picture ideas.

Arousal and Sleep –Reticular formation- controls arousal~ how much/ what information reaches cerebral cortex= how aroused//aware a person is. –Pons and medulla contain centers that cause sleep when stimulated –Midbrain has center that causes arousal. –Serotonin: neurotransmitter that activates sleep centers –Bodily Rhythms –Ultradian: Sleep –Infradian: hormones, seasonal, migration (animals), 28 day cycle (human female) –Circadian: 24/25 hour body clocks (body temperature, bathroom, wakefulness) How do we Study Bodily Rhythms?—Michael Siffre/ cave studies; animals Interval Timing Clocks –helps creatures time their activities –Located in the superchiasmatic nucleus (Richter), in the hypothalamus. The nucleus is responsive to light. Melatonin is a hormone secreted by the endocrine system. The superchiasmatic nucleus regulates the secretion of it. Secretion increases with darkness and decreases with light. Disruptions to rhythm: jet lag, shift workers; [preadaption: gradual match sleep-wake cycles.]

Language and Speech Aphasia: impairment of language, usually caused by left hemisphere damage either to Broca’s area [impaired speaking] or Wernicke’s area [impaired understanding] Broca’s Area: controls language expression; directs muscle movements w/ speech Wernicke’s Area: controls language reception; involved w/ language comprehension Conduction Aphasia: speech is fluent but meaningless. Some comprehension and reading ability, but cannot repeat correctly Global Aphasia: usually with widespread impairment of (damage to Left Hemisphere) all language and functions related Lateralization –Left: speech, language, calculation, ‘rapid serial processing of details.’ –Right: ‘overall context, spatial perception, creative abilities.’